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\documentclass{article}
\usepackage{microtype}
\usepackage[T1]{fontenc}
\usepackage{enumitem}
\newcommand{\currentsection}{3.5}
\setlist[enumerate,1]{label=\currentsection.\arabic*}
\begin{document}
\begin{enumerate}
\item ohai
\begin{enumerate}
\item ok
\item hi
\end{enumerate}
\item oha...